NORMAL GREY:
PLEASE NOTE THAT NORMAL GREY IS NOT A MUTATION BUT THE ORIGINAL COLORING OF THE WILD COCKATIELS, AND IT IS DOMINANT TO ALL COLOR MUTATIONS (EXCEPT DOMINANT SILVER). ALL MUTATIONS ARE VARIATIONS OF NORMAL GREY PLUMAGE, AND ARE CAUSED BY DILUTION, INTENSIFICATION, OR ABSENCE OF THE COLORS FOUND IN GREYS.
LUTINO:
LUTINO CANNOT BE VISUALLY SEXED, MALE AND FEMALE LOOK THE SAME. ALL MELANIN (GREY OR BROWN) IS NOT PRESENT FROM LUTINO COCKATIELS’ PLUMAGE, RESULTING IN A WHITE BIRD WITH THE USUAL YELLOW FACE AND ORANGE CHEEK PATCH. THEIR EYES ARE RED, AND THEIR BEAKS AND FEET ARE PINK. THE RED EYES OF THE LUTINO CAN DISTINGUISH IT FROM A “CLEAR PIED” (A PIED BIRD THAT HAS NO GREY MARKINGS), WHICH WOULD HAVE DARK EYES. LUTINO IS A SEX-LINKED MUTATION. MALES CAN BE SPLIT TO LUTINO, BUT FEMALES CANNOT.
PIED:
PIED ALSO CANNOT BE VISUALLY SEXED, MALE AND FEMALE LOOK THE SAME. PIED BIRDS HAVE RANDOM AREAS OF PLUMAGE THAT CONTAIN NO MELANIN, AND THEREFORE AREAS OF THEIR GREY PLUMAGE ARE REPLACED WITH YELLOW (MOST PIED COCKATIELS HAVE MORE YELLOW FEATHERS THAN GREY ONES). THEY HAVE DARK EYES, WHICH CAN DISTINGUISH THE HEAVIEST PIED (BIRDS WITH NO GREY FEATHERS, OR CLEAR PIED) FROM LUTINOS. THIS MUTATION IS RECESSIVE.
PEARL:
THE PEARL MUTATION, WHICH IS SEX-LINKED, REMOVES THE MELANIN FROM THE CENTERS OF ALL GREY FEATHERS, GIVING THE AFFECTED PLUMAGE A “SCALLOPED” APPEARANCE. WHILE FEMALES RETAIN THIS COLORATION THROUGHOUT THEIR LIVES, MOST MALES LOSE THE PEARL MARKINGS AFTER THEIR FIRST MOLT, AFTER WHICH THEY LOOK LIKE DARK NORMAL GREY BIRDS.
WHITEFACE:
THE MALE IS SOLID GREY WITH A WHITE FACE. WHILE THE FEMALE HAVE BARRING ON THE TAIL AND A GREY FACE, THE WHITEFACES BODY DOES NOT HAVE THE ABILITY TO MAKE THE COLOR YELLOW, THEREFORE THE WHITEFACE IS ONLY WHITE AND GREY, AND DOES NOT HAVE THE YELLOW COLORING AND ORANGE CHEEK PATCHES.
ALBINO:
ALBINO IS ACTUALLY A WHITEFACE-LUTINO. THESE BIRDS CANNOT BE VISUALLY SEXED MALE AND FEMALE. WHITEFACE-LUTINO DO NOT HAVE THE ABILITY TO MAKE THE COLORS YELLOW OR GREY THEREFORE THEY LOOK "ALBINO". WHITEFACE-LUTINO ALSO HAS RED EYES LIKE THE LUTINO.
CINNAMON:
CINNAMON COCKATIELS HAVE A LIGHT TAN COLOR TO A CHOCOLATE BROWN INSTEAD OF THE DARK GREY FEATHERS OF A NORMAL BIRD. THEIR EYES ARE DARK, AND THEIR BEAKS AND FEET ARE GREYISH. CINNAMON IS A SEX-LINKED MUTATION.
FALLOW:
FALLOW COCKATIELS ARE SIMILAR TO CINNAMONS, BUT THEIR EYES ARE RED, THEIR BEAKS AND FEET ARE PINK, AND THEIR BROWN FEATHERS ARE PALER AND YELLOWER THAN CINNAMONS. FALLOW IS A RECESSIVE MUTATION.
SPANGLE:
THIS MAY LOOK VERY SIMILAR TO THE PEARL COCKATIEL, BUT IN FACT IS THE EXACT OPPOSITE PATTERN.
PASTEL FACE:
THIS MUTATION IS VERY CLOSE IN NATURE TO THE WHITEFACE GENE BUT DOES NOT AFFECT THE COLORING AS MUCH. IT ONLY MAKES THE ORANGES AND YELLOWS MORE "PASTEL" LOOKING.
SILVER:
SILVER COCKATIELS HAVE A MUCH DILUTED GREY COLORING THAT LOOKS, WELL, SILVER. THIS ALSO CAUSES YELLOW TO BE MORE PROMINENT. THERE ARE TWO TYPES OF SILVER MUTATIONS: DOMINANT AND RECESSIVE. BOTH TYPES OF BIRDS HAVE A SILVERY GREY APPEARANCE, WHICH IS CAUSED BY A REDUCTION OF MELANIN (THE MATERIAL THAT PRODUCES GREYS AND BROWNS) IN THEIR FEATHERS.
RECESSIVE SILVER BIRDS ARE UNIFORMLY SILVER-GREY, WITH BRIGHT RED EYES AND PINK FEET AND BEAKS. A DOMINANT SILVER COCKATIEL CAN BE EITHER A SINGLE-FACTOR (IT HAS ONLY ONE COPY OF THE AFFECTED GENE) OR A DOUBLE-FACTOR (IT HAS TWO COPIES). DOUBLE-FACTORS ARE LIGHTER THAN SINGLE-FACTORS, JUST AS IF THEY HAD A DOUBLE DOSE OF MELANIN REDUCTION. BOTH TYPES HAVE DARK EYES, BEAKS AND FEET, AND A DARK GREY “SKULLCAP”. THIS MUTATION IS DOMINANT TO ALL OTHER COLORS, INCLUDING GREY. SEE THE GENETICS LESSON FOR AN EXPLANATION OF THE WAY IN WHICH THIS COLOR IS INHERITED.
PAR BLUE (WHITEFACE, PASTEL FACE, AND CREAM
FACE):
CREAM FACE, PASTEL FACE, AND WHITEFACE ARE THREE RECESSIVE MUTATIONS THAT MAKE UP THE PAR BLUE, OR PARTIAL-BLUE, SERIES. ALL THREE MUTATIONS AFFECT THE GENE THAT CONTROLS THE AMOUNT OF YELLOW IN A COCKATIEL’S PLUMAGE.
THE WHITEFACE MUTATION REMOVES ALL YELLOWS AND REDS FROM THE PLUMAGE, GIVING AFFECTED BIRDS A PURE-WHITE FACE. COMBINING FALLOW OR OLIVE WITH WHITEFACE REMOVES THE CHARACTERISTIC YELLOW WASH FROM THESE COLORS, WHITEFACE FALLOWS LOOK LIKE PALE WHITEFACE CINNAMONS, AND WHITEFACE OLIVES LOSE THEIR GREENISH TINGE WHILE RETAINING THE SLIGHT SCALLOPED PATTERN ON THEIR WING FEATHERS.
PASTEL FACE COCKATIELS HAVE A REDUCED AMOUNT
OF YELLOW AND RED IN THEIR PLUMAGE, GIVING THEIR CHEEK PATCHES A PASTEL PEACH
APPEARANCE.
CREAMFACE WHICH IS A NEWER MUTATION AND STILL QUITE RARE, REDUCES THE YELLOW AND RED PIGMENTS EVEN MORE THAN PASTEL FACE, LEAVING JUST A HINT OF CREAM IN THE CHEEK PATCH, AND AN OTHERWISE WHITISH FACE.
OLIVE:
OLIVE, A RECESSIVE MUTATION, HAS ONLY RECENTLY BEEN DEVELOPED AND IS STILL RELATIVELY RARE. OLIVE BIRDS HAVE LIGHT GREY FEATHERS WITH A HEAVY YELLOW WASH, MAKING THE FEATHERS APPEAR ALMOST GREENISH. THERE SEEMS TO BE SOME VARIATION IN THE LIGHTNESS OF THE GREY AMONG DIFFERENT BIRDS SOME ARE MUCH PALER THAN OTHERS. OLIVE BIRDS ALSO HAVE A SLIGHTLY SCALLOPED PATTERN ON THEIR WING FEATHERS, THE EDGES OF THESE FEATHERS ARE DARKER, FADING INTO SLIGHTLY PALER CENTERS.
YELLOW CHEEK (DOMINANT AND SEX-LINKED):
YELLOW CHEEK (CALLED YELLOW FACE) COCKATIELS
HAVE YELLOW CHEEK PATCHES RATHER THAN ORANGE ONES. ONLY THE ORANGE PATCHES ARE
AFFECTED IN THIS MUTATION, WHICH COMES IN TWO FORMS SEX-LINKED AND DOMINANT.
DOMINANT YELLOW CHEEK IS INHERITED IN THE SAME WAY AS DOMINANT SILVER, ALTHOUGH
I HAVE NOT HEARD THAT THERE IS ANY VISIBLE DIFFERENCE BETWEEN A SINGLE-FACTOR
AND A DOUBLE-FACTOR DOMINANT YELLOW CHEEK.
GENETICS LESSON:
WHAT IS A MUTATION?
A MUTATION IS A CHANGE IN A PIECE OF GENETIC MATERIAL. SOME MUTATIONS HAVE LITTLE OR NO EFFECT ON THE ANIMAL (OR ANOTHER LIVING THING) WHOSE GENES THEY ALTER, WHILE OTHERS CAN CAUSE DRAMATIC CHANGE OR EVEN BE FATAL. THE MUTATIONS THAT COCKATIEL BREEDERS ARE MOST CONCERNED WITH ARE HARMLESS, AFFECTING ONLY THE COLORS IN THE BIRDS’ PLUMAGE. THESE COLOR VARIATIONS OCCUR BECAUSE THE MUTATIONS CHANGE THE LEVELS OF MELANIN (WHICH PRODUCES BROWNS, BLUES, AND GREYS) AND LIPOCHROMES (WHICH PRODUCE YELLOWS AND REDS) IN THE BIRDS’ FEATHERS. THE LUTINO MUTATION, FOR EXAMPLE, REMOVES ALL MELANIN FROM A COCKATIEL’S PLUMAGE, AND THE WHITEFACE MUTATION REMOVES THE LIPOCHROMES. A COMBINATION OF THESE MUTATIONS WOULD RESULT IN A PURE-WHITE BIRD.
HOW ARE THE MUTATIONS INHERITED?
GENES COME IN PAIRS; A PAIR IS COMPOSED OF A
GENE FROM EACH PARENT. A MUTATION CAN AFFECT BOTH COPIES OF THE GENE, ONLY ONE COPY,
OR NEITHER. THE DIFFERENT COMBINATIONS OF GENE PAIRS ALTER THE WAY IN WHICH THE
MUTATION AFFECTS THE BIRD; THE EFFECTS OF THESE COMBINATIONS ARE DETERMINED BY
WHETHER THE MUTATION IS DOMINANT, RECESSIVE, OR SEX-LINKED. A DOMINANT MUTATION
NEEDS ONLY TO BE PRESENT IN ONE COPY OF A GENE TO CHANGE A BIRD’S APPEARANCE.
NORMAL GREY (WHICH IS NOT CONSIDERED TO BE A MUTATION, BUT THE WILD COLORATION OF A COCKATIEL) IS DOMINANT TO ALL RECESSIVE AND SEX-LINKED COLORS.
THE TWO TRUE DOMINANT MUTATIONS ARE DOMINANT SILVER AND DOMINANT YELLOW CHEEKS. A BIRD WITH ONE DOMINANT SILVER GENE WILL APPEAR SILVER AND IS CALLED A SINGLE-FACTOR BIRD. A COCKATIEL WITH TWO COPIES OF THE GENE IS CALLED A DOUBLE-FACTOR. THE TWO FORMS CAN BE TOLD APART VISUALLY; A DOUBLE-FACTOR IS MUCH PALER THAN A SINGLE-FACTOR (THINK OF THE DOUBLE-FACTOR AS HAVING INHERITED A DOUBLE DOSE OF MELANIN REDUCTION). DOMINANT YELLOW CHEEK IS INHERITED IN THE SAME WAY AS DOMINANT SILVER, BUT SINGLE-FACTOR AND DOUBLE-FACTOR BIRDS CANNOT BE VISUALLY TOLD APART.
A RECESSIVE MUTATION MUST AFFECT BOTH COPIES OF A GENE IN ORDER TO CHANGE THE BIRD’S APPEARANCE; A VISUALLY WHITEFACE COCKATIEL MUST HAVE INHERITED A COPY OF THE “WHITEFACE” GENE FROM EACH OF ITS PARENTS. A BIRD THAT POSSESSES ONLY ONE COPY OF A RECESSIVE GENE IS CALLED A SPLIT, AND WILL PASS THAT MUTATION ON TO HALF OF ITS OFFSPRING. MOST SPLITS WILL NOT SHOW ANY SIGN OF THE HIDDEN MUTATION, ALTHOUGH COCKATIELS THAT ARE SPLIT TO PIED WILL OFTEN HAVE A PATCH OF YELLOW FEATHERS ON THE BACKS OF THEIR NECKS.
A SEX-LINKED MUTATION IS ONE THAT IS CARRIED ON ONE OF THE SEX CHROMOSOMES. WHEN DEALING WITH SEX-LINKED MUTATIONS IN BIRDS, IT IS IMPORTANT TO NOTE THAT HUMANS’ AND BIRDS’ SEX CHROMOSOMES DO NOT WORK IN THE SAME WAY. WHILE A HUMAN FEMALE IS HOMOZYGOUS (WHICH MEANS THAT SHE HAS TWO COPIES OF THE SAME SEX CHROMOSOME — “XX”) AND A MALE HUMAN IS HETEROZYGOUS (“XY”), IT IS THE OTHER WAY AROUND IN BIRDS; FEMALE BIRDS ARE HETEROZYGOUS, AND MALES ARE HOMOZYGOUS. THIS MEANS THAT FEMALES CAN HAVE ONLY ONE COPY OF A SEX-LINKED MUTATION (THE MUTATION IS CARRIED ON THE X CHROMOSOME), AND IT FOLLOWS THAT FEMALES CANNOT BE SPLIT TO A SEX-LINKED MUTATION. IF A FEMALE DOES NOT VISUALLY POSSESS THE SEX-LINKED TRAIT, SHE DOES NOT CARRY IT AT ALL.
WHAT IS A CROSSOVER?
A MALE COCKATIEL INHERITS ONE X CHROMOSOME FROM HIS FATHER (LET’S CALL THIS CHROMOSOME “X1”) AND THE OTHER FROM HIS MOTHER (“X2”). EACH OF THESE CHROMOSOMES CAN CARRY SEX-LINKED MUTATIONS, AND THE MUTATIONS ON EACH X CHROMOSOME ARE ALWAYS INHERITED TOGETHER SO THE MUTATIONS ON X1 WILL TRAVEL TOGETHER TO THE NEXT GENERATION (LIKEWISE FOR THE ONES ON X2).
LET’S SAY THAT A LUTINO MALE AND A CINNAMON
PEARL FEMALE HAVE ONE MALE CHICK. ONE OF THE CHICK’S X CHROMOSOMES (CALL
IT “X1”) WILL CARRY LUTINO (FROM HIS FATHER), AND THE OTHER (“X2”) WILL CARRY
CINNAMON AND PEARL (FROM HIS MOTHER):
X1: LUTINO
X2: CINNAMON PEARL
IF THIS MALE IS MATED TO A GREY FEMALE, THESE
ARE THE POSSIBLE RESULTS:
MALE CHICKS:
50% GREY SPLIT TO CINNAMON PEARL (IF THEY
INHERIT X2)
50% GREY SPLIT LUTINO (IF THEY INHERIT X1)
FEMALE CHICKS: 50% CINNAMON PEARL (IF THEY INHERIT X2) 50% LUTINO (IF THEY INHERIT X1) NOTE THAT, ACCORDING TO THIS MODEL, IT IS NOT POSSIBLE FOR ANY OF THE FEMALE CHICKS TO BE JUST PEARL, JUST CINNAMON, OR LUTINO PEARL. SHE IS LIMITED TO THE COMBINATION OF MUTATIONS ON THE SINGLE X CHROMOSOME SHE INHERITS.
IN SOME CASES, GENETIC CROSSOVERS CAN OCCUR
WHICH SWITCH THE PLACEMENT OF SEX-LINKED MUTATIONS. CROSSOVERS OCCUR IN
INDIVIDUAL GAMETES WHEN THE MALE PRODUCES SPERM. IN THE EXAMPLE ABOVE, IT
WOULD BE POSSIBLE FOR THE TWO X CHROMOSOMES TO SWITCH SOME GENETIC MATERIAL AND
THUS SWAP MUTATIONS, LEAVING, FOR EXAMPLE, PEARL ON X2 AND TRANSFERRING
CINNAMON TO X1 (MEANING THAT X1 WOULD THEN CARRY BOTH CINNAMON AND
LUTINO). THE AFFECTED GAMETE WOULD THEN PRODUCE EITHER A CINNAMON LUTINO
HEN OR A PEARL HEN (IF THE RESULTING CHICK WERE MALE, IT WOULD BE SPLIT TO
PEARL OR CINNAMON LUTINO). IF YOU KNOW A MALE’S PARENTAGE AND FIND THAT
HIS CHICKS CARRY UNEXPECTED COMBINATIONS OF SEX-LINKED MUTATIONS, A CROSSOVER
IS THE CAUSE. THE RATE OF CROSSOVERS SEEMS TO VARY FROM MUTATION TO
MUTATION, BUT IT CAN BE AS HIGH AS 30%.
WHAT DOES PARBLUE MEAN?
THE WORD “PARBLUE” REFERS TO THE PASTEL FACE, CREAM FACE-WHITEFACE SERIES OF MUTATIONS, WHICH REDUCE THE LEVEL OF YELLOW PIGMENT IN THE COCKATIELS’ PLUMAGE. MANY WILD-TYPE PARROTS HAVE GREEN PLUMAGE DUE TO A COMBINATION OF FEATHER STRUCTURE AND PIGMENTS; MELANIN AND STRUCTURE PRODUCE BLUE FEATHERS, WHICH COMBINE WITH YELLOW PIGMENTS TO CREATE GREEN PLUMAGE. A TOTAL LACK OF YELLOW PIGMENTS, THEN, RESULTS IN A BIRD THAT IS BLUE RATHER THAN GREEN, AND A REDUCTION OF YELLOW PIGMENT CREATES VARYING SHADES OF BLUISH-GREEN, THUS THE TERM “PARTIAL BLUE,” OR PARBLUE.
COCKATIELS’ FEATHERS LACK THE STRUCTURAL FEATURES NEEDED TO PRODUCE BLUE, AND YELLOW/RED PIGMENTS TEND TO BE CONFINED TO THE FACE, SO THE MUTATIONS THAT WOULD CAUSE A BLUE OR PARTIAL-BLUE APPEARANCE IN OTHER PARROTS INSTEAD PRODUCE A GREY-BODIED BIRD WITH A WHITE OR PALE-YELLOW FACE.
ALTHOUGH “REDUCED-YELLOW” DESCRIBES THE
ACTUAL APPEARANCE OF THESE COCKATIELS BETTER THAN “PARBLUE,” IT’S BETTER TO
STICK WITH A TERM THAT’S ACCEPTED BY PARROT BREEDERS INSTEAD OF MAKING UP A
LABEL THAT NO HAS HEARD OF. IF THE EXPERTS CAN AGREE ON A BETTER LABEL
FOR THESE MUTATIONS, THE VIRTUAL BREEDER’S TERMINOLOGY WILL BE UPDATED.
THERE ARE THREE MUTATIONS IN THE PARBLUE SERIES: PASTEL FACE, CREAM FACE, AND WHITEFACE. ALL OF THESE MUTATIONS REDUCE YELLOW AND RED PIGMENTS TO DIFFERENT DEGREES; PASTEL FACE REDUCES THE APPEARANCE OF THESE PIGMENTS BY ABOUT 50%, CREAM FACE BY ABOUT 90%, AND WHITEFACE ELIMINATES THESE PIGMENTS COMPLETELY (THESE PERCENTAGES ARE JUST ESTIMATES). BECAUSE ALL OF THESE MUTATIONS AFFECT THE SAME GENE, WHICH WILL BE CALLED THE “PARBLUE GENE” IN THIS PROGRAM FOR THE SAKE OF CLARITY, THEY INTERACT DIFFERENTLY THAN OTHER MUTATIONS, WHICH CAN BE VERY CONFUSING FOR BREEDERS WHO ARE JUST LEARNING ABOUT GENETICS.
AS YOU LEARNED IN THE GENETICS LESSON,
AUTOSOMAL (NON-SEX-LINKED) GENES COME IN PAIRS, AND THE PARBLUE GENES ARE
AUTOSOMAL. THIS MEANS THAT A BIRD CAN CARRY A MAXIMUM OF TWO MUTATIONS
FROM THE PARBLUE SERIES: ONE CREAM FACE AND ONE PASTEL FACE MUTATION, OR TWO
WHITEFACE MUTATIONS, OR ONE NORMAL GENE AND ONE PASTEL FACE MUTATION, JUST TO
NAME A FEW POSSIBILITIES. AS LONG AS A BIRD CARRIES TWO MUTATED COPIES OF
THE PARBLUE GENE EVEN IF THE TWO MUTATIONS ARE NOT THE SAME THE BIRD WILL NOT
BE NORMAL GREY. INSTEAD, THE BIRD WILL HAVE THE APPEARANCE, OR PHENOTYPE,
OF THE “YELLOWEST” OF THE TWO MUTATIONS IT CARRIES. A BIRD CARRYING ONE
PASTEL FACE AND ONE CREAM FACE MUTATION, THEN, WILL LOOK EXACTLY LIKE A PASTEL
FACE; A BIRD WITH ONE WHITEFACE AND ONE CREAM FACE MUTATION WILL LOOK LIKE A
CREAM FACE.
IN THE VIRTUAL BREEDER, WHAT DO X1 AND X2
MEAN?
IF THE MALE YOU ENTER IS SPLIT TO ONE OR MORE SEX-LINKED MUTATIONS, THE BREEDER WILL LET YOU SPECIFY WHICH OF THE MALE’S TWO X CHROMOSOMES (X1 AND X2, AS THEY ARE NAMED HERE) CONTAIN THESE MUTATIONS (THIS APPLIES ONLY TO SPLITS, SINCE A VISUAL SEX-LINKED MUTATION OCCUPIES BOTH CHROMOSOMES). FOR THE SAKE OF ORDER, LET’S SAY THAT X1 IS THE CHROMOSOME HE INHERITED FROM HIS FATHER, AND X2 IS THE ONE HE GOT FROM HIS MOTHER. IF HE ONLY HAS ONE SEX-LINKED MUTATION, IT DOESN’T MATTER WHETHER YOU PUT IT ON X1 OR X2 THE RESULTS WILL BE THE SAME. OF COURSE, IF YOU KNOW THAT YOUR MALE IS THE RESULT OF A CROSSOVER, ASSIGN THE MUTATIONS ACCORDINGLY. IN THE LIST OF RESULTS, ANY SEX-LINKED SPLIT MUTATIONS WILL BE FOLLOWED BY THE X CHROMOSOME IT OCCUPIES. AT THIS TIME, THE VIRTUAL BREEDER IN THE COCKATIEL COLOR PALETTE APP INCLUDES CROSSOVER POSSIBILITIES, BUT THE ONLINE VIRTUAL BREEDER DOES NOT.
WHY ISN'T ALBINO AN OPTION IN THE VIRTUAL BREEDER?
THERE IS NO TRUE ALBINO MUTATION IN
COCKATIELS (YET). WHEREAS A TRUE ALBINO COCKATIEL WOULD BE THE RESULT OF A
SINGLE MUTATION, THE ALL-WHITE COCKATIELS THAT ARE OFTEN CALLED ALBINOS ARE
ACTUALLY THE RESULT OF COMBINING THE WHITEFACE AND LUTINO MUTATIONS THE TWO
MUTATIONS WORK TOGETHER TO REMOVE ALL PIGMENT FROM THE BIRD, JUST AS A TRUE
ALBINO MUTATION WOULD.
WHY DON'T MY CHICKS MATCH THE VIRTUAL BREEDER'S RESULTS?
THE PARENT BIRDS CARRY UNKNOWN SPLITS.
IF YOU HAVE TWO GREYS, THE VIRTUAL BREEDER
WILL TELL YOU THAT ALL OF YOUR PAIR’S CHICKS WILL BE GREY. IF THEIR CHICKS, TO
YOUR SURPRISE, ARE FALLOW, PEARL, AND WHITEFACE (JUST AS AN EXAMPLE), YOU KNOW
THAT YOUR TIELS HAVE BEEN HIDING SOMETHING FROM YOU THEIR SPLITS. IF YOU AREN’T
FAMILIAR WITH YOUR PAIR’S PARENTAGES, THEY MAY BE SPLIT TO ANY NUMBER OF
MUTATIONS, AND YOU WON’T HAVE ANY WAY OF KNOWING UNTIL THEY PRODUCE CHICKS WITH
MUTATIONS YOU DIDN’T EXPECT. ONCE YOU SEE “NEW” MUTATIONS IN THE CHICKS, YOU
CAN DEDUCE WHAT THE PARENTS’ SPLITS MUST BE. FOR EXAMPLE, IF TWO GREYS PRODUCE
A PEARL CHICK, YOU KNOW THAT THE MALE GREY MUST BE SPLIT TO PEARL (AND THE
PEARL CHICK MUST BE FEMALE). IF THE GREYS THEN PRODUCE A WHITEFACE CHICK, YOU
KNOW THAT BOTH PARENTS MUST ALSO BE SPLIT TO WHITEFACE. THIS KIND OF DETECTIVE
WORK CAN GET COMPLICATED, BUT IT’S FUN. WELL, IN MY OPINION, ANYWAY!
A GENETIC CROSSOVER HAS OCCURRED.
WE’LL USE TWO GREYS AS AN EXAMPLE AGAIN. IF
YOU KNOW FOR A FACT THAT YOUR GREY MALE IS SPLIT TO {X2: LUTINO PEARL}, BECAUSE
HIS MOTHER WAS A LUTINO PEARL, YOU WOULD EXPECT HALF OF HIS DAUGHTERS TO BE
GREY AND A HALF TO BE LUTINO PEARL. IF ONE OF HIS DAUGHTERS TURNS OUT TO BE A
REGULAR PEARL, THE CAUSE IS A GENETIC CROSSOVER. CROSSOVERS HAPPEN RELATIVELY
RARELY, BUT IF YOUR MALE IS SPLIT INTO MORE THAN ONE SEX-LINKED MUTATION, YOU
CAN PROBABLY EXPECT TO SEE AT LEAST ONE CHICK WHICH DOESN’T INHERIT THOSE
MUTATIONS IN AN EXPECTED WAY. THE VIRTUAL BREEDER DOES NOT YET TAKE CROSSOVERS
INTO ACCOUNT IN ITS PREDICTIONS, BUT THIS FUNCTIONALITY MAY BE ADDED IN THE
FUTURE.
PROBABILITY ISN’T AN EXACT SCIENCE.
IF THE VIRTUAL BREEDER IS TELLING YOU THAT
YOU’LL GET PIED CHICKS 50% OF THE TIME, BUT NONE OF YOUR PAIR’S 8 CHICKS ARE
PIED, THAT’S JUST ONE OF THE QUIRKS OF PROBABILITY. THE PARENT BIRDS’ GENES
COMBINE RANDOMLY TO CREATE EACH CHICK, AND EVEN THOUGH WE CAN PREDICT THAT A
CERTAIN COMBINATION WILL OCCUR 25% OF THE TIME, IT MIGHT HAPPEN 90% OF THE
TIME, OR IT MIGHT NEVER HAPPEN. THEORETICALLY, THE MORE CHICKS A PAIR PRODUCES,
THE MORE CLOSELY THE CHICKS’ TYPES WILL REFLECT THE PERCENTAGES EXPRESSED BY
PROBABILITY. IF YOUR PAIR HAS A MILLION CHICKS, YOU MAY WELL SEE THAT ALMOST
EXACTLY 50% OF THE CHICKS ARE PIED. BUT THEN YOU’D HAVE TO FIND HOMES FOR A
MILLION CHICKS.
തിരുവനന്തപുരം THIRUVANANTHAPURAM
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THIS CONTENT IS COPYRIGHTED BY AKHILCHANDRIKA. ANY UNAUTHORIZED REPRODUCTION,
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